INDIANAPOLIS — Using scientific techniques and cutting-edge equipment, researchers at the Indianapolis Museum of Art Conservation Science Laboratory have recently solved mysteries about paintings by Vincent van Gogh and Giorgio de Chirico. Since opening in early 2011, the Conservation Science Laboratory has undertaken multiple projects that have provided the museum world with new research, techniques, and advances in the field of conservation.

A partnership between the IMA Conservation Science Laboratory and the Cincinnati Art Museum (CAM) has shed new light on the colors that Vincent van Gogh used in his 1890 painting "Undergrowth with Two Figures." Van Gogh was known to use vibrant colors in his paintings, but many of his works today have lost this original vibrancy. Undergrowth with Two Figures is one such work and during a cleaning of the work, former CAM paintings conservator Per Knutas unearthed minuscule traces of bright pink colorant in areas where the frame covered the edge of the painting. This discovery prompted Knutas to contact Dr. Gregory D. Smith, the IMA Otto N. Frenzel III senior conservation scientist. Smith agreed to help identify the paint colorant used by van Gogh and worked with visiting researcher Dr. Jeffrey Fieberg, associate professor of chemistry at Centre College in Danville, Ky., to examine the painting and solve the mystery.

"I gladly accepted the challenge to identify the colorant, knowing this project would allow the Conservation Science Laboratory to build ongoing partnerships within the museum community, contribute useful research on paint fading, and fully utilize the state-of-the-art instruments available in the lab," Smith said. "This project is a shining example of the type of research the lab is equipped to conduct."

Van Gogh painted Undergrowth within the last five weeks of his life - a period when he was known to have used a bright Geranium Lake organic dye - and the brilliance of Geranium Lake is short lived when exposed to light. A helpful clue in the process came from a letter written by van Gogh to his brother, Theo, while he was painting the work stating it contained "... undergrowth, lilac trunks of poplars, and underneath them some flower-dotted grass, pink, yellow, white, and various greens." Since the pink flowers rapidly faded to white, the question addressed by the IMA lab was which flowers were white because of the fading, and which ones were always white.

The painting was brought to the IMA for an in-depth, nondestructive analysis. Smith utilized a small broken paint chip found lodged in the varnish to analyze the dye by Raman microspectroscopy - a process that collects a characteristic spectral fingerprint from the dye by measuring changes in laser light scattered by the molecules. Comparison of the spectrum to a digital library of thousands of materials identified the dye as eosin, which gives Geranium Lake its vibrant color. After identifying the ink, Smith and Fieberg painstakingly mapped out its location by elemental spectroscopy in the 387 daubs of white paint used by van Gogh to represent the flowers. The team used Adobe Photoshop to record all the spots in which the dyestuff was detected, creating a virtual restoration of the aged painting.

The research collaboration between Smith, Fieberg, and CAM is ongoing. An upcoming scholarly publication by the project's core collaborators will make the information more widely known to art history scholars. Smith is now working with forensic scientists at Indiana University-Purdue University Indianapolis to refine the coloration used in the virtual restoration based on actual microcolorimetry measurements of small paint flakes from the van Gogh painting.

Van Gogh said, "... in the colours there is adulteration as in wines. How can one judge correctly when, like myself, one knows nothing of chemistry." Although the damage has already been done, through chemistry the IMA is now working to understand the changes in this work and others by van Gogh in the museum's collection and to give today's admirers of his work a more accurate picture of his artworks' brilliance.

The Conservation Science Lab did similar work on a Giorgio de Chirico painting from the IMA's permanent collection. IMA Associate Curator for Research, Annette Schlagenhauff, gained assistance from the science lab and conservation imaging specialists while studying the provenance and authenticity of de Chirico's "The Mysterious Departure." The piece was taken off view for more than 30 years because of the belief that it might be a forgery. Closer examination revealed a figure study underneath that was characteristic of de Chirico's later works. It is now believed that de Chirico painted this work in the 1930s as a copy of one of his earlier pieces to take advantage of the popularity of this metaphysical style later in his career.